Lighting fixture



June 23, 192 5. 1 1,543,606

W. HARRISON LIGHTING FIXTURE Filed Feb. 24, 1920 ,5 [ZVSZENTDR m map5622231501? Hrs EPW032222:

Patented June 23, 1925.-

UNITED STATES PATENT OFFICE.

WARD HARRISON, or CLEVELAND, onro, ASSIGNOR T0 GENERAL ELECTRIC 001v:-

PANY, A CORPORATION OF NEW YORK.

. LIGHTING FIXTURE.

Application filed February 24, 1920. Serial No. 360,774.

To all whom it may concern:

Be it known that I, WARD HARRISON a citizen of the United States,residing at Cleveland, county of Cuyahoga, State of Ohio,-have inventedcertain new and useful Improvements in Lighting Fixtures, of which thefollowing is a specification.

This invention relates to lighting units and pertains especially tounits for semiindirect lighting.

The object of this fixture is to secure the recognized advantages ofsemi-indirect lighting, that is illumination in which the greaterpart ofthe lighting comes from large expansive ceilings, without its recognizeddisadvantages. The common way of securing such illumination, is tosuspend an open bowl of opal glass below the ceiling and equip it withclear bulb incandescent lamps. The disadvantages of this plan are,first, that the open bowl and the exposed lamp collect interfere withthe efiiciency of the unit Second, that with the concentrated filamentsnow commonly used in-incandescent lamps, the edge of the bowl throws asharp shadow; on the ceiling or on the high side walls, which detractsfrom the appearance of the installation, and undesirable shadows of thechains or others supports for the fixture also appear. Several previousattempts or inventions have been made with the view to eliminatingshadows but in all of these cases the result has been obtained only by agreat sacrifice in the efliciency of the unit.

According to my invention, a unit is provided having two sections anupper section of which is clear glass and a lower section of translucentor semi-transparent glass. The clear section of the unithas. been madewith a comparatively steep slope so that, so far as possible, the dustwill slide off. Furthermore, there is but this one surface exposed, thelamp bulb itself and the interior of the unitbeing completely closedoff. In ordinary fixtures about one-half of the loss is due tocollection. of dust on the lamps themselves. The contour of the upper orclear section of the unit is so designed that all of the images of thefilament reflected thereby are directed back into the bowl and,therefore, cannot reach the eye of the observer. In my first experimentsthe absence of this contour was productive of glare.

dust rapidly which seriously An embodiment of my invention is shown inthe accompanying drawing in which Fig. 1 is a side elevation partiallyin sec tion of the main portion of my improved lighting unit and Fig. 2is an assembled view of a complete unit.

Referring to the drawings, 10 represents a high efficiency tungsten lampwhich is housed in my improved globe 11. The upper clear glass portion12 of this is shown as being formed substantially on the surface of asphere. This particular conformation has been designed for two purposes.First it prevents a reflected image of the filament becoming visible tothose in the room as the ray lines 13 and 13 which are received from thelight source 14 strike the globe at 15 and 15' and are redirecteddownwardly to the lower portion 16 of the globe 11 which is ofsemi-transparent reflecting material secured, for-instance, by coatingwith enamel or by the use of translucent glass. Second, no dust canaccumulate on the clear glass portion due to its particular shape whichallows the dust to roll off entirely or collect at the bottom which istranslucent and where it will not affect the efiiciency of the unit.

Instead of having a sharp line of demarcation between the clear andenamelled sections of this fixture, I which has been characteristic ofall previous uses of enamel in lighting glassware, the coating has beenallowed to taper off gradually at 17 so there is no sharp line.Therefore, there is no objectionable shadow from the edge cast by thebowl against the side walls or ceiling. The chain shadows have beeneliminated by suspending the unit from the neck rather than from theoutside of the bowl. The neck 17 of the globe 11 must necessarily be ofsufficient size to admit the lamp 10, hence the cap inclosing thisopening would ordinarily ,cast a shadow on the ceiling which would bequite as objectionable as chain Shadows themselves. This difliculty hasbeen overcome, however, bymaking a fixture 18 at its point of contactwith the ceiling of substantially the diameter of the shadow cast by thecap. The boundaries of this shadow are shown by lines 19 which extendfrom the light source 20 to the outside of the canopy 21. Now when theunit is lighted, the .fixture simply appears of somewhat darker colorthan the ceiling ad M5 pleasing.

5 indirect bowl to enhance its appearance.

Those decorations or color tones ordinarily subtract very materiallyfrom the efiiciency of the light unit with the fixture described. Suchresults can be obtained with approxi- Ml mately no loss in efficiency byequipping the lamp with an opal cap 22 which cap reflects the largeportion of the light to the ceiling and transmits simply enough light torender the globe luminous and The opal glass cap 22 is held in positionby the coiled spring holder 23 which has extensions 24 fastened at 25 inthe cap 22, the spring holder 23 fits over the neck of the lamp 10 andis under tension thus keeping the cap tightly around the lamp at alltimes.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

An integral inclosing globe for artificial light sources having itswidth greater than its depth and comprising a lower portion at leastpartially reflecting and extending below said light source, and an uppertransparent portion having the contour of a portion of a sphere with itscenter at the light source extending over said light source.

In witness whereof, I have hereunto set my hand this 18th day orFebruary, 1920.

WARD HARRISON.

